Small intestine bacterial overgrowth (SIBO), is a digestive condition that is being spoken more and more about, you will see more blog and social media posts talking about it, this is in large part due to the improved availability of testing options, as well as practitioners becoming more informed about the distinctions in gut function that make this a specific area for consideration in the average clients journey to health freedom.
It is categorised by abnormally large numbers of commensal (bugs that are natural, normal, supposed to be living within us) bacteria normally making a home for themselves in the large intestine then becoming resident in the small intestine. SIBO is a common cause of IBS – in fact it is involved in over half the cases of IBS and as high as 84% in one study using breath testing as the diagnostic marker. Breath testing is the new technique of choice for SIBO identification. Its been found that reducing the bacterial overgrowth leads to a 75% reduction in IBS symptoms.
Bacterial overgrowth leads to impairment of digestion and absorption, and in turn produces excess quantities of hydrogen and/or methane gas. These gases are produced as the product of metabolism, specifically of fermentation (breaking down for digestion) of carbohydrates by your gut bacteria. When commensal bacteria multiply in the small intestine to the point of overgrowth, IBS is likely. Hydrogen/methane breath testing is the most widely used method of testing for this overgrowth.
Some people think SIBO is IBS, correctly referred to as a functional digestive system disorder, and some people think SIBO is something totally different from IBS, and others think SIBO is IBD, Inflammatory Bowel Disease, mostly common of two types, Ulcerative Colitis and Crohn’s Disease. Then there are others that have never heard of SIBO.
I have spoken to many clients that have been to their doctors with IBS type symptoms, mostly constipation, diarrhoea or both and left feeling it must all be in their head and can do no more than suck it up buttercup. I have worked with some of these people that started off feeling like they must be mostly exaggerating it and decided it probably was all in their heads, more a symptom of depression, low self esteem and lack of purpose in life. Only to find out it was a gluten intolerance, which is very real and biochemical, you measure it, get a number and work to reduce that number and reduce the associated symptoms. Then there are clients with what seems like IBS that turn out on testing, confirmed to be SIBO. In others identifying a gluten issue is found to be a symptom of loss of gut function, imbalance in good bacteria levels, and an inappropriate response of the immune system.
I am saying all this not to make it confusing and look like it’s impossible to figure out what you have going on or what to then do about it, but to show that the body is complex, the digestive and immune system are complex, however if you collect the right information and consider deeper and more thorough investigation you can absolutely figure out what your actual issues are.
People routinely say, “I eat a healthy diet!”, well clearly not as they have symptoms. Healthy for them and healthy in general are not the same thing, close but sometimes not close enough. I can get told its IBS and they just need to get on the peppermint oil again or arrange another course of antibiotics. I also can help with issues that develop from people that just prefer to ignore their gut problems and crack on regardless. Maybe they ignore a problem food to avoid the symptom.
However, if your assumption is that the body will just then repair itself, and all will be good as new again, you can quite often be mistaken. Taking away the problem of course helps, especially if it was a problem that has been gong on for years, however its very likely that in the absence of the offending food extra steps need to be taken to restore order and rebuild previous resistance. Maybe during the period the offending food was offending their gut there was associated issues of inflammation of the gut lining, less good bacteria (probiotics), an increase in enzymes that impact detoxification or breakdown and elimination of your hormones or reduction in the production of the enzymes you need to fully breakdown and gain the nutrients and energy from your food.
Can you be sure that all returns to normal just by removing dairy that seems to cause your diarrhoea, or gluten that causes your headaches or those strawberries that give you an itchy throat? Its quite possible, and this can be a chicken and egg scenario, but there is underlying bugs, some are pathogenic (disease causing) and some are opportunistic. The pathogenic nasty bugs can make you very sick and then pass in days or weeks. The opportunistic bugs, literally see their opportunity when defences are down and bed in for the long haul sucking up your resources. A stool test that is expansive (and therefore more expensive) will investigate all this from the bugs, good, bad or indifferent to the function of your digestive system and in part your immune system. Is there inflammation or reduced digestive capacity, these can be assessed and then decisions made on the best course of action.
Once we have the stool test, and sometimes also adding food sensitivity testing, we can be more sure we are looking at IBS. If however you have uncovered and then removed hidden food intolerances, introduced a more mindful approach to meals, less about how fast can you eat or skip meals, and then got more functional by restoring production of digestive acid, digestive enzymes and bile acids and there are still symptoms such as bloating, abdominal pain, constipation, or diarrhoea that have remain unchanged, and ruling out more serious digestive issues, thats where SIBO as a serious consideration typically comes in.
I would always want a thorough discussion on your health history, what you have tried before and didn’t work, how long has this been an issue, combined with symptom scoring questionnaires and then combine this with testing for digestive function, that can include a stool test, breath test for SIBO (see more information below), and food sensitivity testing. Sometimes we need to know about the effect of stress and hormone balance to manage the stress response to begin the healing journey. Other times tests that identify imbalances in metabolism or liver function, including detoxification of environmental chemicals or heavy metals have to be included. For others a strong steer to your design limitations and genetic strengths and weaknesses come DNA testing. Each person is evaluated as an individual and we can then discuss the road forward, this can quite often be simple are other times it needs to be more in-depth.
A stool test looks at bugs in your stool that is the product of your large intestine. Bacteria, parasites, and fungi are supposed to live in your large intestine, just not necessarily in excessive numbers. However when the symptoms point to Small Intestinal Bacteria Overgrowth, some of these large intestine bacteria have stayed in the small intestine or moved to there instead. There are factors that can be considered in a stool test that help support what we are looking at is a SIBO issue, which is a great help, but then we need to pinpoint is it SIBO, what gases are highest, what do the levels mean and then we have a baseline for action.
What causes SIBO?
Somewhere in amongst the, bad bugs and bad food story, there are changes in the function of the digestive system indicated by a slowing of motility, a fancy way of saying food slows down in its transit time through the digestive system, most commonly categorised by constipation, gas and belching.
Principal cause of SIBO – decreased gut motility
The decrease in gut motility can be caused by several factors such as:
- Health conditions such as Hypothyroidism (low thyroid gland function) and Diabetes
- Surgery (nerve damage)
- Certain medications (especially opiates)
- Physical obstructions: Tumours, surgical adhesions, or hairpin turns in the bowel (can block the path to clearing away bacteria)
- Non-draining pockets: Diverticuli (pockets off the side of the small intestine collect debris which cannot be cleaned out)
One of the key mechanisms the body uses to make sure the bacteria in your digestive system ends up where it’s supposed to end up is the migrating motor complex or MMC for short. When it is active it acts like a kind of cleansing wave which is the “housekeeper” of the small intestine, clearing bacteria from the small intestine and moving them down into the large intestine. The MMC mostly does its work when we are fasting, so on a normal daily basis that would be during the night and between meals. Eating late at night and up early for breakfast and work as well as consuming snacks during the day is a sure fire lifestyle to encourage the development of slower passage of food through the intestine and therefore more bacteria remaining in the small intestine.
A well known primary cause of decreased motility is acute gastroenteritis (food poisoning, stomach flu, or traveler’s diarrhoea), something many of us experience at some point in our lifetime. When we say bad bugs, pathogens, are toxic we mean they produce toxins. Some of these bacteria produce a protein that is toxic and binds to nerve cells in the small intestinal lining. Our immune system thinks it looks like the toxin actually on the bacteria surface so due to whats called “Molecular Mimicry” the body attacks both bad bug and good, nerve cell. This attack on the nerve cell when it is part of the MMC prevents proper functioning.
Factors leading to development of SIBO
There are also factors which can increase the likelihood of developing SIBO by encouraging bacterial overgrowth these include:
- Pathogens
- Ileocaecal valve (the gateway valve/sphincter muscle that controls entry to the large intestine from the small intestine) dysfunction (when this valve gets “stuck open,” it allows bacteria to back up from the large intestine into the small intestine and accumulate where it doesn’t belong)
- IBS and IBD and chronic Coeliac Disease
- Organ system dysfunction, such as liver cirrhosis, chronic pancreatitis, or renal failure
- Multiple courses of antibiotics
- Overconsumption of sugar or alcohol
- Low stomach acidity (in part as that leads to more pathogens within the digestive system) or use of acid-blocking medications
As I mentioned persistent constipation that also coincides with painful or significant bloating are key clues that we need to be considering for confirmations of the presence of SIBO but these following symptoms are also very common:
- Abdominal pain/discomfort
- Bloating and abdominal distention
- Diarrhoea
- Constipation
- Gas and belching
- Weight loss and symptoms related to vitamin deficiencies (more severe cases)
Long term issues with presence of SIBO
It has been shown to alter the structure and function of the small intestine to in turn significantly interfere with digestion of food and absorption of nutrients, primarily by damaging the cell lining, the mucosa. This damage to the mucosa can in time lead to Leaky Gut (or intestinal barrier permeability, allowing protein molecules, that are too large, to escape into the bloodstream). This can lead to chronic immune reactions that cause food allergies or sensitivities, generalised inflammation, and autoimmune diseases.
The pathogenic bacteria, can be too many or the wrong types, lead to nutritional deficiencies on top of those due to poor digestion or absorption seen with Leaky Gut. When you were little and your parents said you had worms due to all the food you were eating, the inference was your worms were eating your food, instead of you, and as it happens the worms well can be worms (sorry I know thats gross and no one wants to think about that). When they are bacteria, these bacteria will absorb or eat some of your B vitamins (eg Vitamin B12) instead of you and in part that is connected to the desire, in fact need to consume more nutrition, that can be interpreted as the requirement for more cake or more vegetables.
If some of your amino acids are also swallowed up by your greedy bacteria, wrongly living in your small intestine, where the majority of the nutrition from your food is absorbed, then a mild protein deficiency can develop. These bacteria, with cool names like Klebsiella, Proteus and Pseuodmonas, that you are feeding also can increase the amount of ammonia produced.
It is a normal part of metabolism to produce some ammonia and your detoxification system will happily deal with that. The problem comes when if you are not the healthiest it’s quite likely you need a greater focus on detoxification, and an overloaded detoxification system cant cope with all the extra demands including bacteria produced ammonia . Ammonia has toxic effects in the gut that can cause a change in the dominant bacterial composition to reduce the numbers of beneficial bacteria. It gets worse. The bacteria may also decrease fat absorption by decreasing the production of necessary bile acids, the result is fat soluble vitamins like A and D become deficient.
If SIBO is present and as mentioned it can alter nutrient absorption then minerals like iron can be affected as well and in time bring about conditions such as anaemia. Gut health has such far reaching consequences for our whole body health, it really should be a priority and not just considered when things go significantly wrong. It is pretty common to hear about anaemia and find out a new client has been taking iron supplements. Iron supplements are normally recommended off the back of a blood chemistry test but a properly assessed blood test should evaluate functional capacities, deficiencies and need for further testing to discover underlying causes.
This is a functional medicine or nutritional therapy perspective and of course your medic should evaluate medical results. Therefore, I am not saying iron supplements are not warranted just that gut health if found to be dysfunctional needs to be resolved for holistic, whole body health and better function. Without considering the body as a whole and the role of gut health you can start working with a client that has been round the merry go round of taking this for that ailment and one test point here and the other there all within resolution and commonly health suffering.
SIBO associated medical conditions
Anaemia is a serious medical concern and there are other diseases associated with SIBO beyond those mentioned above:
- Lactose Intolerance
- Systemic Sclerosis
- Chronic Pancreatitis
- Fibromyalgia/Chronic Regional Pain Syndrome
- Hepatic Encephalopathy
- Non-Alcoholic Steatohepatitis
- Interstitial Cystitis
- Restless Leg Syndrome
- Acne rosacea
Key Indicators for SIBO versus IBS
Some of the key indicators that more strongly point to SIBO over IBS and stool testing versus a breath test include:
- Developing IBS symptoms after suffering food poisoning
- If antibiotics seem to have made a big difference in symptoms after a course of antibiotics
- If steps to improve digestive symptoms only make matters worse; probiotics with prebiotics and/or increasing fibre
- If you have Coeliac Disease and remove gluten but symptoms don’t improve
How best to test for SIBO
A stool test is definitely a valuable tool, if you know what you are looking for and have a thorough health history and current complaints but going in for the nitty gritty in this case requires a breath test. We measure the levels and types of gases given off over a 4 hour period, once the bugs if they are living in the wrong place are fed a specific sugary solution to make them really gassy, and you breath into test tubes. We can then evaluate the balance of hydrogen versus methane. The bacteria chew up the sugar solution, we can’t absorb it.
How to reduce bacteria living in the wrong place and cut back on the gas
A doctor would work with you using antibiotics and likely radical diet (eg. Elemental Diet) if SIBO is identified. My approach is based on:
- Personalising and modifying diet to lower fermentable carbohydrates (especially eliminating grains, starch, starchy veg, lactose, sucrose)
- Improve digestive capacity
- Gut repair
- Gut motility
- Bacterial elimination
There are several ways to implement the above suggestions and of course with my preference for lab testing I would always look to test and properly identify your exact issues and go from there to design an approach that works for you.
If you’re not sure what to eliminate from your diet, whether its a direct result of a food sensitivity or a functional issue such as SIBO, long term avoidance of various foods can in time lead to different, unintentional consequences such as nutrient deficiencies.
It can be really tricky working out what your health challenges are, but with the right approach and lab testing at the centre used as a deeper level of insight, then combined with experience drastic changes do happen.